Scientific name: Morone saxatillis
The striped bass was once commercially important in Eastern Canada and is still highly prized by anglers. It is an anadromous species – meaning that it spawns in fresh water before moving downstream to brackish and salt water to feed and mature. It is dark olive green on the back with paler silvery sides and white on the belly. Seven or 8 dark stripes run horizontally down its sides. Striped bass is a long lived fish, reaching up to 30 years of age. Although it has been recorded at lengths up to 1.8 m, it rarely reaches 1 m in Canadian waters.
The natural range of the striped bass extends along the Atlantic coast of North America, from the St. Lawrence Estuary to the St. Johns River in northeast Florida. Native striped bass populations have also existed in the tributaries of the Gulf of Mexico, from the Suwannee River in northwestern Florida to Lake Pontchartrain in Louisiana.
There is historical evidence of striped bass spawning in five rivers of Eastern Canada: the St. Lawrence Estuary, the Miramichi River in the southern Gulf of St. Lawrence, and the Saint John, Annapolis and Shubenacadie rivers, which all drain into the Bay of Fundy. Striped bass still spawn in the Miramichi (southern Gulf) and Shubenacadie (Bay of Fundy) rivers. The Bay of Fundy is also frequented by striped bass that breed in rivers in the United States.
The species was also introduced on the U.S. Pacific coast in the late 1800s, where it became established. Many lakes and reservoirs in the southern U.S. have been stocked with striped bass to promote the sport fishery.
The species is typically associated with estuaries and coastal waters. An abundant striped bass population is an indicator that a river and its estuary are in good condition: the species requires high quality spawning and nursery habitat and abundant aquatic species for food. Striped bass is an important component of the biodiversity of aquatic ecosystems.
Striped bass spawn in freshwater and occasionally brackish water. Egg incubation, larval and young-of-the-year development correspond to a gradual movement downstream to saltwater, where they typically feed and grow for several years before reaching maturity.
A particular feature of Canadian striped bass populations is that they overwinter in rivers in order to escape the cold ocean waters.
The striped bass can live and, in some cases, complete its entire life cycle in freshwater, although there are no known freshwater striped bass populations in Canada.
Increasing water temperatures in the spring trigger the movement of striped bass to their spawning grounds in fresh or slightly brackish waters. Spawning (which can last up to 3 to 4 weeks for large spawning aggregations) tends to take place at twilight when temperatures rise above 10o C. Eggs are suspended in the water column for 2 to 3 days before hatching. Larvae require an abundant supply of zooplankton (minute organisms that live in the water column) to survive. Striped bass remain at the larval stage for 35 to 50 days before they undergo a metamorphosis to their juvenile form at which point they are approximately 20 mm long.
Young-of-the-year move downstream over the summer where they continue to feed and grow in estuaries and coastal bays. Older fish migrate along the coast in search of prey, which includes small fishes such as juvenile herring, smelt and tomcod. In the fall, Canadian populations of striped bass move back upstream where they overwinter in brackish or fresh water, likely to avoid low ocean temperatures.
Males reach maturity sooner than females at roughly 3 years of age. Females mature at anywhere from 4 to 6 years of age. Adults are repeat spawners, with females producing between 50,000 and 1.5 million eggs.
Historically, three rivers draining into the Bay of Fundy supported striped bass spawning populations, but repeated spawning failures led to the disappearance of the Annapolis and Saint John River populations. These disappearances are thought to be due to changes in the water’s flow, and a degrading water quality. In the Shubenacadie River population, the only remaining spawning population in the Bay of Fundy, the presence of the introduced chain pickerel in overwintering sites may constitute a threat. Another threat to the population is bycatch from various commercial fisheries.
In more detail
The Annapolis River has shown no evidence of spawning or recruitment since 1976. Concerns are that agricultural pollution, pesticides or changes in pH have affected egg and larval survival. The construction of the Annapolis Royal causeway, near the mouth of the river may also have altered incubation and rearing habitat, further affecting recruitment. A recreational fishery for striped bass is concentrated at the base of the dam in summer and fall.
The Saint John River has supported both a recreational and commercial fishery. A commercial fishery in Belleisle Bay was conducted in winter from 1930 to 1978 when it was determined that there was an absence of recruitment and the population was in decline. The last evidence of spawning was in 1979. Like the Annapolis River, alterations in rearing habitat due to dam construction (the Mactaquac Dam was built in 1967) and pollution may also have inhibited the survival of eggs and larvae.
The Shubenacadie River today supports a relatively stable population of striped bass with spawning occurring in the Stewiacke River, a tributary of the Shubenacadie. Abundance estimates from a recreational fishery which takes place from April to June indicate a decline happened between 1950 and 1975. Early estimates from more recent tagging programs and surveys suggest the population has stabilized. Members of the population migrate to Grand Lake in winter where there is potential for them to be illegally taken in the ice fishery for smelt.
Courtesy of Species at Risk Public Registry, Government of Canada